This invention relates to the transfer of particulate matter, and more particularly pertains to a rotary feeder construction which efficiently transfers said matter at desirably high, controlled rates to a zone of use from a supply source.
In prior art processes for feeding particulate material by means of rotary feeders, various expedients have been employed to effect desired feeding of such material to a zone of use. Thus, in Kidd U.S. Pat. No. 3,593,891 which issued July 20, 1971, a star feeder is provided in which a rotatable wheel is eccentrically mounted relative to the surrounding casing wall whereby the teeth thereof form an air seal when approaching the incoming material to be fed and are subsequently spaced from the casing wall in the course of rotation. Conveying pockets formed by the wheel teeth may thus carry the material into a feed line.
In Stern U.S. Pat. No. 3,223,288 which issued Dec. 14, 1965, a feeder employing rotating vanes having fluid passageways is employed in which the clearance between each of the vane distal edges and the housing wall is maintained as small as possible. In Woods U.S. Pat. No. 3,556,606 which issued Jan. 19, 1971, the flow of carbon black from a rotary feeder is maintained uniformly by a by-pass loop disposed about the rotary valve inter-connecting a supply hopper and zone of use whereby excessive pressure build-up in said supply hopper may be relieved.
The apparatus of this invention comprises a rotary feeder employing a rotatable valve having radially extending vanes secured at their proximal ends to a central rotatable shaft. The valve is rotatable within a feeder housing communicating with a supply source of the particulate material to be fed, such as a hopper, and a conduit leading to a zone of use for such particulate material.
In accordance with this invention alternate vanes of the rotatable valve have clearances interposed such vanes and the surrounding housing wall. Such clearances may take the form of notches in the vane edges, apertures through the vane bodies or intervals between the vane distal edges and the casing wall.